One-fifth of the genome codes for secretory proteins;a small subset of these proteins represent peptide hormone signaling molecules. This proposal addresses the identification of novel secretory molecules involved in the control of metabolic function. Since the majority of neuroendocrine signaling molecules undergo proprotein convertase-mediated maturation, we plan to exploit the presence of genuinely cleavable sites in novel precursors to validate a set of potential peptide precursors. We will then test the bioactivity of correctly modified peptide products derived from these proteins. These assays will identify biologically active peptides acting on tissues that are key effectors of metabolic control: fat, liver and muscle. The proposed project represents a collaboration of the Lindberg laboratory with the secretory protein company Five Prime Therapeutics. Briefly, bioinformatics identification of large numbers of putative precursors by Five Prime will be followed by screening of HEK-expressed proteins with purified recombinant convertases (Lindberg laboratory). The information generated by the processing screen will then be used to direct large-scale recombinant protein production of promising precursors in the Lindberg laboratory. These purified precursors will be subjected to in vitro proteolytic and terminal maturation reactions in the Lindberg laboratory, and the resulting peptide products will then be tested in six metabolic assays targeted at fat, liver and muscle cell glucose metabolism at FivePrime Therapeutics. We expect that these studies will result in the identification of several novel peptide hormones contributing to metabolic control. These results should aid in our complete understanding of the hormonal control of glucose and lipid metabolism. PUBLIC HEALTH RELEVANCE: This is a discovery project which focuses on the identification of novel bioinformatics-identified peptide hormones. We will employ chemical processing of candidate precursors using physiological enzymes to make peptide mixtures which we will test in six different assays of glucose and lipid metabolism. We expect that these studies will result in the identification of several novel peptide hormones contributing to metabolic control.